IJMPCERO  Vol.4 No.4 , November 2015
Gamma-Index Passing Rates in Baseline Plans Measured with a Detector Array
ABSTRACT
Purpose: This study provides a simple protocol for validation of the gamma passing rates and to identify the optimum values of % dose and mm criteria for dose distributions measured with a detector array. Methods: We chose ArcCHECK detector array to illustrate the concepts. We used plans with uniform or quasi-uniform dose distributions along the detector array for testing in the presence of dose errors. For testing sensitivity to spatial shift we employed a plan with approximately constant dose gradient along the axis of the instrument. Results: We identified a representative set of parameters which describe performance of a detector array. We determined the minimum gamma-index acceptance criteria allowing the passing rates to reach 100% in the absence of errors, and identified the minimum fully detectable errors for such criteria. For our baseline plans delivered to ArcCHECK, 100% passing rates were obtained for 1.5% dose criterion together with ±3% minimum error detectable at 100% rate, and for 1.5 mm criterion together with the minimum fully detectable error of ±3 mm. We inspected the impact of selected program options on the passing rates. Conclusions: The protocol we developed provides a simple method of commissioning- analysis of a detector array without a need for analysis of a large number of clinical plans.

Cite this paper
Szpala, S. and Kohli, K. (2015) Gamma-Index Passing Rates in Baseline Plans Measured with a Detector Array. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 4, 326-337. doi: 10.4236/ijmpcero.2015.44039.
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